This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 12 |
| 5 | 62 |
| 6 | 385 |
| 7 | 2781 |
| 8 | 22848 |
| 9 | 210176 |
| 10 | 2139336 |
| 11 | 23872450 |
| 12 | 289825228 |
| 13 | 3803859030 |
| 14 | 53676793157 |
| 15 | 810508456373 |
| 16 | 13041332257860 |
| 17 | 222776899815744 |
| 18 | 4026846590787586 |
| 19 | 76792054455516582 |
| 20 | 1540845309830989064 |